Carrier for high frequency signals having conducting wires with roughness portions and a carrier layout method

Abstract

A carrier for transmitting a high frequency signal and a carrier layout method thereof are provided. The carrier includes a substrate, conducting wires and reference planes both formed on the substrate. The carrier layout method includes defining impedance and thickness of the carrier according to the high frequency signal and defining layout parameters according to the impedance and the thickness. The layout parameters include a conducting layer formed on the conducting wires, a coplanar waveguide encompasses both the reference planes and the conducting wires as a part thereof, roughness portions formed on the conducting wires, recessed portions formed on the conducting wires, and the substrate being a high loss tangent substrate. The layout is performed according to the layout parameters defined thereabove, so as to increase loss of the high frequency signal in transmission.

1. A carrier for transmitting a high frequency signal, comprising a substrate, conducting wires and reference planes both formed on the substrate, and characterized by at least one of a conducting layer formed on the conducting wires, a coplanar waveguide that encompasses both the reference planes and the conducting wires as a part thereof, roughness portions formed on the conducting wires, recessed portions forming on the conducting wires, and the substrate being a high loss tangent substrate for increasing high frequency signal loss wherein the roughness portions satisfy equations σ c =σ/Kw 2  and Kw=1+exp(−(s/2h) 1.6 ), wherein electrical conductivity is denoted by σ, skin effect parameter is denoted by Kw, roughness by h, skin depth by s, and electrical conductivity of roughness portion by σ c . 
     
     
       2. The carrier of  claim 1 , wherein the conducting layer is a layer of nickel. 
     
     
       3. The carrier of  claim 1 , wherein the roughness portions are provided on at least a side of the conducting wires. 
     
     
       4. The carrier of  claim 1 , wherein the carrier is one selected from the group consisting of a circuit board, a bus line, and a flexible circuit board. 
     
     
       5. The carrier of  claim 1 , wherein the recessed portions satisfy the equation s=(π×f×u×σ c ) (−1/2) , wherein frequency is denoted by f and permeability by u. 
     
     
       6. The carrier of  claim 1 , wherein unit loss (R) of the signal in a circuit board satisfies equation R=σ c /(w×s), wherein electrical conductivity of said roughness portion is denoted by σ c , trace width by w, and cross-sectional area by (w×s). 
     
     
       7. The carrier of  claim 1 , wherein the conducting wires are of a thickness (T), the thickness satisfying cross-sectional area equation w×T−(w−2s)(T−2s)=2s (w+T)−4s 2 , wherein trace width is denoted by w. 
     
     
       8. The carrier of  claim 1 , wherein the recessed portions are formed on at least a side of the conducting wires. 
     
     
       9. The carrier of  claim 1 , wherein the substrate is an organic fiberglass (FR4) substrate. 
     
     
       10. A carrier layout method of transmitting a high frequency signal, comprising steps of:
 defining impedance and thickness of a carrier according to the high frequency signal being transmitted; 
 defining layout parameters according to the impedance and the thickness, wherein the carrier comprises a substrate, conducting wires and reference planes both formed on the substrate, and the layout parameters are characterized by at least one of forming a conducting layer on the conducting wires, forming a coplanar waveguide to encompass both the reference planes and the conducting wires, forming roughness portions on the conducting wires, forming recessed portions on the conducting wires, and the substrate being a high loss tangent substrate; and 
 performing layout according to the layout parameters defined, so as to increase loss of the high frequency signal being transmitted; 
 wherein the roughness portions satisfy equations σ c =σ/Kw 2  and Kw=1+exp(−(s/2h) 1.6 ) , wherein electrical conductivity is denoted by σ, skin effect parameter is denoted by Kw, roughness by h, skin depth by s, and electrical conductivity of roughness portion by σ c . 
 
     
     
       11. The method of  claim 10 , wherein the conducting wires are of a thickness (T), the thickness satisfying cross-sectional area equation w×T−(w−2s)(T−2s)=2s (w+T)−4s 2 , wherein trace width is denoted by w. 
     
     
       12. The method of  claim 10 , wherein the carrier is one selected from the group consisting of a circuit board, a bus line, and a flexible circuit board. 
     
     
       13. The method of  claim 12 , wherein, in the step of defining layout parameters according to the impedance and the thickness, the carrier is a circuit board, and the step of defining layout parameters further comprises evaluating board thickness required for layout design. 
     
     
       14. The method of  claim 10 , further comprising a step of performing surface treatment for forming the conducting layer on the conducting wires. 
     
     
       15. The method of  claim 14 , wherein the surface treatment is performed by one of electroplating and sputtering. 
     
     
       16. The method of  claim 10 , wherein Electroless Nickel and Immersion Gold (ENIG) is performed so as to increase thickness of the conducting layer. 
     
     
       17. The method of  claim 10 , wherein unit loss (R) of the signal transmitted by the carrier satisfies equation R=σ c /(w×s), wherein electrical conductivity of said roughness portion is denoted by σ c , trace width by w, and cross-sectional area by w×s. 
     
     
       18. The method of  claim 10 , wherein the recessed portions satisfy the equation s=(π×f×u×σ c ) (−1/2) , wherein frequency is denoted by f and permeability by u.